Multiple switch for use in connection with electric welding machines



May 19, 1925. l,538,4l0 E. SCHROEDER IUIJ'I'IPLJQ SWITCH FORv USE INCONNECTION WITH ELEGT RIC WELDING MACHINES Filed June 20 1923 .ErZm247702 fidy ezien Patented May 19, 1925.

UNITED STATES PATENT OFFICE.

EDMUND SCHROEDER, OF BERLIN, GERMANY.

MULTIPLE SWITCH FOR USE IN CONNECTION WITH ELECTRIC WELDING MACHINES.

Application filed June 20, 1923. Serial No. 646,663.

To all whom time y concern:

Be it known that I, EDMUND SoHRoEDER, a citizen of the Republic ofGermany, residing at Berlin, in the Republic of Ger many, have inventedcertain new and useful Improvements in Multiple Switches for Use inConnection with Electric \Velding Machines; and I do hereby declare thatthe following is a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same.

T his invention relates to a multiple switch for use in connection withelectric welding machines operating with a current interrupted inregular short intervals, for instance steam welding machine operatingaccording to the so-called roll-step method (U. 8. Patent 1,488,867).

Switch mechanism in accordance with the present invention ischaracterized by the feature that several contacts are adapted toconnect a monophase transformer alternatively with each of the phases ofa polyphase current system in such a way that during operation, auniform load on all the phases is attained. In this way, a one-sided orunilateral load, which has a very bad effect on small systems, for whichreason such ma chines are often prohibited from being connected to thosesystems, is avoided.

Other objects of the invention will be in part obvious and in partpointed out hereinafter.

In order that the invention and its mode of operation may be readilyunderstood by persons skilled in the art, I have in the accompanyingillustrative drawing, and in the detailed following description basedthereupon, set out an embodiment of the same.

In these drawings Figure 1 shows diagrammatically a multiple switchdevised according to the present invention; and,

Figure 2 is a plan view of the cam discs and rollers therefor.

The ends of the primary monophase transformer coil T are connected withfour contacts a, 7), c, (I, one end of said coil being connected withthe contacts a and b, the other with the contacts 0 and cl. The wiresa2, 31 and z of the multiple phase net or polyphase current system areconnected with four swinging contacts I, Ia, II, and III, the firstphase a: being connected with the contacts I and Ia, the second 3 withthe contactII, the third 2 with the contact III. Coiled springs f tendto draw the contacts III, I, la, and II against their stationarycounter-contacts o, I), 0, (Z, whereas cam disks m, a, 0, p, areprovided in order to interrupt the closed contacts at certainpredetermined times. The cams of the disks are so arranged that aftereach pause another phase is connected up to the coil T.

Supposing, the cam disks rotate-in. the direction indicated by thearrows, and their position be just that shown in the drawing Each diskis assumed to be divided into six segments 1, 2, 3, l, 5, 6, and thearrangement and length of'the cams proper relatively to the segments isconstantly that illustrated, whereas their position relatively to rollsR provided at the free ends of the swinging contact levers changesin apredetermined succession. In the position shown the contacts III/a. andII /d are closed which means that the coil T is connected up, at thetime being, to the phase II/III. At other times, in determinedsuccession and constant repetition, the coil T is connected with thecontacts III/a and Ian/0, or is connected up to the phase I/IIIrespectively; or with the contacts I/b and II/ol, or up to the phaseI/II respectively. All contacts are open when the segments bearing oddnumbers cooperate with the rolls R,'there being then a pause between theclosing of two contacts. The coil T is connected with the phase I /IIIat the segments 2, with the phase I/II at the segments 4, and with thephase II/III at the segments 6. Thus, each phase is under load whilstthe cam disks make one revolution, the loads are equal during this time,and there is a pause between each change of phases The cam disks are, infact, located not in one plane, as might be assumed from thediagrammatical representation in Figure 1 of the drawing, but they arelocated side by side as shown in Figure 2 on. a common shaft rotated bysuitable means.

If the switch is used in connection with a welding machine operatingwith step-wise roll movement, the number of revolutions of the cam disksmust'be one third of the number of steps caused by the driving shaft ofthat machine.

Another valuable advantage the improved multiple switch offers is thisthat it permits to attain, for a given period of time, threefold thenumber of interruptions possible W phase transformer, a plurality ofcontacts connected each with a. phase of a multiplephase net, and meansto connect up alternately said coil with said contacts in a successionin which all phases are equally loaded during a period of time extending15 over several changes of the connections, as set forth.

In witness whereof I have hereunto set my hand.

EDMUND SCHROEDER.

